1. Technical Field
The present invention relates to surgical instruments and more particularly, to an endoscopic surgical instrument having a flexible drive mechanism.
2. Background of Related Art
Articulating surgical instruments are well known in the art. Surgeons typically use articulating instruments to reach areas out of line with the entry axis of the surgical instrument. Ordinarily, articulating surgical instruments transmit energy along a longitudinal axis of the instrument, and do not effectively transmit large amounts of energy when the end effector is articulated at sharp angles. Surgical instruments that use high force/low velocity methods often require physically large components. These physically large components are usually quite rigid and are not easily bent.
The operation of current articulating surgical instruments involves the movement of a rod or a long flexible metal strip actuator around a bend. The use of such structural elements leads to, among other things, friction and buckling. These adverse consequences are normally minimized by restricting the maximum bend angle of surgical instruments to approximately 45 degrees.
For instance, U.S. Pat. No. 5,381,943 to Allen et al. discloses an endoscopic surgical stapling instrument comprising a pivotable staple head assembly mounted on the distal end of a support tube. The instrument includes a handle assembly and a saddle-shaped actuator slidably mounted thereon for controlling the pivotal movement of the staple head assembly. An articulation driver is mounted inside the support tube. The articulation driver is formed by an elongated thin flat rod. In operation, the saddle-shaped actuator moves a slide member coupled to a driver coupling member to operate the articulation driver. The articulation driver pivots the stapling head assembly in response to movement of the saddle-shaped actuator. The staple head assembly can be articulated to angles of 15, 30, 45 and 60 degrees relative to the support tube.
In light of current articulating surgical instruments shortcomings, it would be beneficial to provide a surgical instrument capable of bending at angles of at least 90 degrees and transmit the energy required to operate a surgical tool, such as an end effector. It would also be desirable to provide a surgical instrument capable of transmitting large amounts of force at very large angles using simple and reliable structural elements. Therefore, a need exists for a reliable surgical stapling device and a mechanism for use therewith that will allow a user to operate a surgical tool at angles of at least 90 degrees relative to the entry axis of the surgical instrument.